I have finally found you! I bought a print of this and at MCM Comic Con in Manchester, UK back in the summer and the vendor couldn't remember who the artist was.
I have them both on my office wall at home! I love them both very much, you are very talented. ^^
DON'T F%^& WITH MY LITTLE SISTER!
I bought this in Otakuthon 2013, my goodness I love it! She's trying to take out those who are threaten her, or her sister, or haters...